Isolation and Characterization of a Novel <i>Klebsiella michiganensis</i> Bacteriophage RSU-F4K5

Background: Bacteriophage diversity of Klebsiella -infecting phages isolated on Klebsiella spp. other than Klebsiella pneumoniae remains relatively underexplored. Materials and Methods: A novel bacteriophage RSU-F4K5 infecting a Klebsiella michiganensis strain representing ST191 was isolated and characterized. The phage was subjected to Whole Genome Sequencing (WGS), genome de novo assembly, genome functional annotation, and comparative genomics. Wet-lab characterization included Transmission Electron Microscopy (TEM), lysis dynamics turbidimetry, adsorption assay, and a one-step growth curve. Results: K. michiganensis phage RSU-F4K5 is a novel lytic siphophage with a complete genome of 48,657 bp (47.71% G + C) predicted to encode 103 proteins and demonstrating &lt;70% intergenomic similarity to other publicly available phage genomes. Phage RSU-F4K5 failed to infect local Klebsiella spp. isolates other than its isolation host. Conclusions: The host-specificity demonstrated by RSU-F4K5 makes it highly unlikely to be useful for therapeutical applications. However, the isolation and characterization of phage RSU-F4K5 adds to the global knowledge of the phage diversity of Klebsiella spp.